[libcxx] [llvm] [libc++] Updates the compilers used post LLVM-20 branching. (PR #126564)

[Nikolas Klauser via llvm-commits]

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@@ -12,7 +12,7 @@
 // UNSUPPORTED: c++03
 
 // TODO: Investigate these failures which break the CI.
-// UNSUPPORTED: clang-18, clang-19, clang-20
+// UNSUPPORTED: clang-18, clang-19, clang-20, clang-21
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philnik777 wrote:

IIRC the last time it mostly worked except in the optimized build. I've disabled it for everything, since it was already the same day as the LLVM 20 branch and the test was already disabled for all the other versions. We should look into it and maybe just disable it for the optimized build.

https://github.com/llvm/llvm-project/pull/126564